Influence of Pre-Dawn Water Potential and Soil-To-Leaf Hydraulic Conductance on Maximum Daily Leaf Diffusive Conductance in Two Oak Species

1989 ◽  
Vol 3 (6) ◽  
pp. 719 ◽  
Author(s):  
P. B. Reich ◽  
T. M. Hinckley
Keyword(s):  
Water Potential ◽  
Hydraulic Conductance ◽  
Leaf Hydraulic Conductance

scholarly journals Effects of Pinus taeda leaf anatomy on vascular and extravascular leaf hydraulic conductance as influenced by N-fertilization and elevated CO2

2016 ◽  
Vol 3 ◽  
pp. e007 ◽  
Author(s):  
Jean-Christophe Domec ◽  
Sari Palmroth ◽  
Ram Oren
Keyword(s):  
Water Potential ◽  
Pinus Taeda ◽  
Leaf Anatomy ◽  
Environmental Changes ◽  
Water Movement ◽  
Stomatal Closure ◽  
Hydraulic Conductance ◽  
N Availability ◽  
Leaf Hydraulic Conductance ◽  
Bordered Pits

Silvicultural practices (e.g., nitrogen addition through fertilization) and environmental changes (e.g., elevated [CO2]) may alter needle structure, impacting mass and energy exchange between the biosphere and atmosphere through alteration of stomatal function. Hydraulic resistances in leaves, controlling the mass and energy exchanges, occur both in the xylem and in the flow paths across the mesophyll to evaporation sites, and therefore largely depends on the structure of the leaf. We used the Free-Air Carbon dioxide Enrichment (FACE) experiment, providing a unique setting for assessing the interaction effects of [CO2] and nitrogen (N) supply to examine how leaf morphological and anatomical characteristics control leaf hydraulic conductance (Kleaf) of loblolly pine (Pinus taeda L.) trees subjected to ambient or elevated (+200 ppmv) CO2 concentrations (CO2a and CO2e, respectively) and to soil nitrogen amendment (N). Our study revealed that CO2e decreased the number of tracheids per needle, and increased the distance from the xylem vascular bundle to the stomata cavities, perturbing the leaf hydraulic system. Both treatments induced a decrease in Kleaf, and CO2e also decreased leaf extravascular conductance (Kextravascular), the conductance to water flow from the xylem to the leaf-internal air space. Decline in Kleaf under CO2e was driven by the decline in Kextravascular, potentially due to longer path for water movement through the mesophyll, explaining the decline in stomatal conductance (gs) observed under CO2e. This suggests that the distance from vascular conduits to stomata sub-cavity was a major constraint of leaf water transport. Across treatments our results showed that needle vein conductivity was slightly more limited by the lumen than by the bordered-pits, the latter accounting for 30-45% of vein resistance. CO2e-induced reduction in Kleaf was also consistent with an increased resistance to xylem collapse due to thicker cell wall. In addition, stomatal closure corresponded to the water potential inducing a reduction in 50% of leaf vascular conductance (Kvascular) via xylem wall rupture. The water potential that was estimated to induce complete xylem wall collapse was related to the water potential at turgor loss. Our study provided a framework for understanding the interaction between CO2e and N availability in affecting leaf anatomy, and the mechanisms for the response of Kleaf to the treatments. These mechanisms can be incorporated into predictive models of gs, critical for estimating forest productivity in water limited environments in current and future climates and a landscape composed of sites of a range in soil N fertility. 

scholarly journals Leaf hydraulic safety margin and safety–efficiency trade-off across angiosperm woody species

2020 ◽  
Vol 16 (11) ◽  
pp. 20200456
Author(s):  
Chao-Long Yan ◽  
Ming-Yuan Ni ◽  
Kun-Fang Cao ◽  
Shi-Dan Zhu
Keyword(s):  
Water Potential ◽  
Global Analysis ◽  
Safety Margin ◽  
Woody Species ◽  
Hydraulic Conductance ◽  
Plant Distribution ◽  
Mean Annual Precipitation ◽  
Leaf Hydraulic Conductance ◽  
Hydraulic Safety ◽  
Hydraulic Safety Margin

Leaf hydraulic conductance and the vulnerability to water deficits have profound effects on plant distribution and mortality. In this study, we compiled a leaf hydraulic trait dataset with 311 species-at-site combinations from biomes worldwide. These traits included maximum leaf hydraulic conductance ( K leaf ), water potential at 50% loss of K leaf (P50 leaf ), and minimum leaf water potential ( Ψ min ). Leaf hydraulic safety margin (HSM leaf ) was calculated as the difference between Ψ min and P50 leaf . Our results indicated that 70% of the studied species had a narrow HSM leaf (less than 1 MPa), which was consistent with the global pattern of stem hydraulic safety margin. There was a positive relationship between HSM leaf and aridity index (the ratio of mean annual precipitation to potential evapotranspiration), as species from humid sites tended to have larger HSM leaf . We found a significant relationship between K leaf and P50 leaf across global angiosperm woody species and within each of the different plant groups. This global analysis of leaf hydraulic traits improves our understanding of plant hydraulic response to environmental change.

scholarly journals Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf

2014 ◽  
Vol 66 (5) ◽  
pp. 1303-1315 ◽  
Author(s):  
Kevin A. Simonin ◽  
Emily Burns ◽  
Brendan Choat ◽  
Margaret M. Barbour ◽  
Todd E. Dawson ◽  
...  
Keyword(s):  
Water Potential ◽  
Transpiration Rate ◽  
Hydraulic Conductance ◽  
Leaf Hydraulic Conductance

scholarly journals Analysis of a hybrid numerical method – decomposing leaf hydraulic conductance

2018 ◽  
Vol 5 (1) ◽  
pp. 98-112
Author(s):  
Frank H. Lynch ◽  
Gretchen B. North ◽  
Breeanna S. Page ◽  
Cullen J. Faulwell
Keyword(s):  
Numerical Method ◽  
Hydraulic Conductance ◽  
Leaf Hydraulic Conductance ◽  
Hybrid Numerical Method
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